Health Canada is warning patients and health-care professionals about a potentially fatal side-effect related to the drug Sprycel taken by patients with certain forms of leukemia. Sprycel (dasatinib), used to treat adults with chronic myeloid leukemia or acute lymphoblastic leukemia, has been linked to pulmonary arterial hypertension, a condition in which blood pressure is increased in the pulmonary arteries that carry blood from the heart to the lungs. Pulmonary arterial hypertension, a subtype of pulmonary hypertension, is a rare, severe and progressive disease with no apparent cause. It can lead to severe fluid retention in the body, shock and even death.